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Billings, MT Noise from Specific Sources: HVAC & Mechanical Noise (2026)

Some Restrictions
Compiled from the official code textEditor Martyn O'NeillLast verified September 2026

Key Facts

Residential day limit
65 dB(A) max / 55 dB(A) avg
Residential night limit
55 dB(A) max / 45 dB(A) avg
HVAC not on exemption list
treated as non-exempt source
Measured at
complainant's property line
Enforcement
trained/qualified city officials only

Summary

Air conditioners, heat pumps and other mechanical equipment count as a non-exempt noise source in Billings and must stay under the zone's dB(A) ceiling around the clock.

(a)The permissible noise exposure limits from non-exempt noise sources in residential, commercial and industrial districts are as provided in Table 1 below. ... Residential 65 dB(A) [day] / 55 dB(A) [night] ... (b)At boundaries between zones, the lower of the dB(A) level shall be applicable.

View official code

Official source re-checked September 7, 2026: no newer edition of the code had been published (publisher’s edition: Code of Ordinances: Supplement 66 Update 2).

Full Breakdown

Billings' noise chapter doesn't name air conditioners or heat pumps in its exemption list (Sec. 17-105), so running HVAC equipment is treated as a "non-exempt noise source" governed by the numeric limits in Sec. 17-103's Table 1. In a residential zone that's 65 dB(A) maximum / 55 dB(A) average by day (7:00 a.m.-8:00 p.m.) and 55 dB(A) maximum / 45 dB(A) average at night (8:00 p.m.-7:00 a.m.), measured at the complaining neighbor's property line. A unit that trips those numbers, or that a trained city official finds is a loud, unnecessary noise disturbing a neighborhood under Sec. 17-102, is a public nuisance.

Violations & Fines

Municipal infraction with civil penalties under Sec. 18-1304 via Sec. 17-108(a); each day the noisy unit keeps running is a separate offense, and the city can also seek a restraining order or injunction as a public-nuisance remedy.

Frequently Asked Questions

Is there a specific HVAC noise rule in Billings?
No standalone HVAC section. Sec. 17-105's exemption list omits mechanical equipment, so AC and heat pump noise falls under the general dB(A) limits in Sec. 17-103.
What decibel level can my Billings neighbor's AC unit legally hit at night?
In a residential zone, no more than 55 dB(A) maximum (45 dB(A) average) between 8:00 p.m. and 7:00 a.m., measured at your property line.
Who measures the noise for a complaint?
Only trained, qualified city officials using an ANSI-standard sound level meter; third-party consultant readings can't be used to issue a violation under Sec. 17-106.

Sources & Official References

Other rules in Billings

Parking Rules: Overnight ParkingSignificant RestrictionsNoise Ordinances: Quiet HoursSome RestrictionsLow-Frequency Bass LimitsSignificant RestrictionsBar & Nightclub NoiseSome RestrictionsGenerator NoiseSome RestrictionsNoise Ordinances: Amplified Music & Outdoor SoundSome RestrictionsNoise Ordinances: Barking DogsSome RestrictionsParking Rules: EV ChargingSome RestrictionsParking Rules: Driveway RulesSome Restrictions

All Billings rules

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